What is shift work?

Shift work is the way hours of work are organized for an organization to operate outside regular hours. Different types of shifts include

• shifts that rotate or change
• shifts that are split apart by several hours
• permanent shifts (day or evening)
• changing shift lengths (8, 10 or 12 hours)

This fact sheet provides information on shift work that includes some night work.

Who works shift work?

About one quarter of workers in industrialized countries work shifts.

Shift work is important in service industries like health, transportation, communication and utilities where 24 hour services are necessary. Shift work is also needed in some industries where the work cannot be stopped.

For example, petroleum refining cannot be stopped without damaging the product.

Unfortunately, the use of shift work in other industries has increased over the last 20 years.

The body's natural rhythms

Humans are naturally active during the day and sleep at night. Our bodies have a cycle of about 25 hours. This cycle controls many body functions including

• temperature
• digestion
• blood pressure
• pulse
• release of hormones
• repair and maintenance

Your body takes clues from your environment. These clues include light and dark, and sleeping and eating. This helps to keep your body's rhythm in balance with the 24-hour rotations of the earth.

When you change your daily activities from day to night, your body's natural rhythms are disrupted. In fact, our bodies can never truly adapt to night work because of the length of time that we would need to adapt.

The effects of shift work

Digestive problems

Shift work can cause problems with digestion including ulcers, stomach and bowel problems, and a decrease in appetite.

Heart disease

Shift work may play a role in heart disease. Some studies have shown higher cholesterol levels and higher blood pressure among shift workers than among day workers. Both contribute to heart disease.

Other health problems

Shift work can make some health conditions worse such as diabetes, epilepsy, asthma and depression.

Sleep problems

People need to sleep. Shift work affects how much sleep and the kind of sleep that you get. Sleep during the day is not as deep or refreshing as night sleep. The shift worker's time to sleep happens at a time when the body naturally gears up for activity. When you do not sleep enough, you may always feel tired.

Safety concerns

Many night workers feel sleepy during their shift. Sleep loss and the body's disrupted natural rhythms cause sleepiness. You may feel so sleepy that you fall asleep on the job. As a result, you may not do your job properly and safely.

Social and family problems

Shift work causes problems with a worker's life outside work. Participation in social activities and family life is difficult since these activities are often when you are at work. Lack of contact with family and friends can result in feelings of loneliness and isolation.

Solutions to shift work

Organizations

Improving the design of shift schedules can reduce the effects of shift work. There is no perfect shift schedule. But schedules can be improved in these ways

• avoid a permanent night shift
• limit the number of night shifts worked in a row
• avoid an early start for the morning shift
• avoid quick shift changes
• reduce long work shifts and overtime
• give as many weekends off as possible with at least two days off in a row
• keep schedules regular & give workers notice of schedules well ahead of time
• give enough rest breaks

Organizations should try to meet the individual needs of workers. They can provide

• flexible time for child care needs or long travel time to work
• time off for special family or community events
• education for workers to help them cope with shift work
• alternative work for workers who cannot work shift work

Organizations can also help by providing a work environment for shift workers with

• good lighting
• proper ventilation
• clean rest and meal areas
• Individuals

If you have a medical condition like diabetes, asthma, epilepsy, or mental health problems you should ask your doctor's advice before becoming a shift worker.

If you work shifts, you can improve your sleep by a regular bedtime. Make sure to

• have time to relax
• avoid caffeine, smoking and sleeping pills
• lower the bedroom temperature
• make the bedroom dark
• eliminate noise

Eat high protein meals before work. Avoid high protein, high fat and greasy foods for six hours before bedtime.

If you have a workplace health and safety committee, ask them to review this fact sheet. They can make recommendations to reduce the effects of shift work and improve shift schedules for you and your coworkers.

Revised January 2000